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    <meta charset="UTF-8">
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    <title>Document</title>
</head>

<body>
    <script>
        // 整型 : Integer    浮点数 : float 
        let score = '99.7';

        // 1. 字符串转化为 number
        score = parseFloat(score);    // 输出为99.7
        // score = parseInt(score);   // 输出为99
        console.log(score);         // 输出为99
        console.log(typeof score);  // 输出为number

        // 2. not a number
        score = parseInt('剑圣');  // 输出为NaN
        console.log(score);

        // 3. 强制转化为 number
        let age = Number('123');
        console.log(typeof age);  // number
    </script>
</body>

</html>